Weather across the nation: 12/12/12

An active weather pattern continued across the southeastern corner of the nation today, while a Pacific frontal system spread wet weather conditions across the West.

In the East, showers and thunderstorms developed along and ahead of a nearly stationary cold front that extended from the western Atlantic Ocean through the central Florida Peninsula and into the Gulf of Mexico.

As this boundary dropped slowly southward through the day, waves of energy formed along the boundary, combined with a decent plume of subtropical moisture. This caused light to moderate rain showers with periods of heavy rain to develop from the Eastern Gulf Coast through the Carolinas.

Showery weather is expected to spread to the Virginia coast by tonight.

Elsewhere in the East, high pressure prevails across the rest of the region with generally dry conditions. A few scattered lake-effect snow showers with brief intermittent bursts of snow redeveloped off of the northeast end of Lake Erie in New York's interior. Snowfall amounts in these areas were very little to none through the afternoon.

Behind this activity, a few flurries and light snow showers continued across parts of the Northern Plains and Upper Great Lakes as a frontal boundary lingered in the northern tier of these regions with limited moisture.

Out West, a strong and cold frontal system from the Pacific Ocean moved inland and reached from the Northern Intermountain West through central California by afternoon.

Rain showers spread southward through California as this system dropped through the state, while lower accumulations of snow and scattered snow showers occurred in the Sierra Nevadas.

Snow accumulations of 3 to 4 inches were possible at the valley floors, while 4 to 8 inches were possible in most valleys, and 8 to 16 inches were possible for elevations above 7,000 feet.

Snow showers also developed across the Intermountain West and Northern and Central Rockies. Snow accumulations of 6 to 9 inches of snow were anticipated in the valleys, 9 to 18 inches for mountains above 7,000 feet, and nearly 2 feet of snow in the highest elevations.

A fierce storm hit the San Francisco Bay Area on this date in 1995. At a PG&E sensor in Alameda County, winds were measured to 135 mph until the sensor was blown away. The storm knocked out power to 1.5 million people and caused 169 schools to close in the region.